1. Technical Field
The present invention relates to an image forming apparatus.
2. Related Art
In order to match an output density to a target density in a conventional electro-photographic image forming apparatus, a technology is known in which a patch image is formed to measure the density thereof, and an image forming condition is adjusted so that a difference between the measured density and the target density is reduced. In the electro-photographic image forming apparatus, generally, an image holding member is electrically charged to form an electrostatic latent image by exposure light based on image data, and the latent image is developed with a developer, which includes a toner, so as to create a toner image. Because the relationship (output characteristic) between the toner image density formed in this manner and the image data depends on the image forming condition, such as the intensity of exposure light or a developing bias, it is necessary to adjust, for example, the intensity of exposure light or the developing bias to an appropriate value in reproducing the target density. This adjustment of the image forming condition is hereinafter occasionally referred to as “setup.”
When, for example, the environmental temperature or environmental humidity of the image forming apparatus varies, the chargeability of the developer varies, and consequently, the developing property varies. Therefore, it is desirable to acquire an appropriate image forming condition by performing the setup.